苹果触摸启动图像加载错误的分辨率图像

Question

I'm doing a Sencha Touch web app with splash screens specified as follows. The images are 640x920 and 320x460 respectively (allowing for the statusbar and following an example from Sencha).

<link rel="apple-touch-startup-image" media="screen and (resolution: 326dpi)" href="/resources/img/startup_640.png" />
<link rel="apple-touch-startup-image" media="screen and (resolution: 163dpi)" href="/resources/img/startup.png" />

However, on an iPhone 4, I'm still seeing only the low resolution image. (To make things easy, I've embedded the text "640x920" and "320x460" in the appropriate image to be sure I'm looking at the right images.)

I keep clearing the Safari cache and reloading the app, but the wrong image continues to load.

Just to make sure I had them right, I switched the links to point to the opposite files, but then as expected, neither splash loaded.

Any other suggestions?

EDIT: Similarly, the apple-touch-icon-precomposed is loading the smaller of the two as well.

Answer 1

This will add a Splash Screen to your Web App. Below are the sizes you'll need for both iPad and iPhone/iPod Touch, these include the status bar area as well.

<!-- iPhone -->
<link href="http://www.example.com/mobile/images/apple-startup-iPhone.jpg" media="(device-width: 320px) and (device-height: 480px) and (-webkit-device-pixel-ratio: 1)" rel="apple-touch-startup-image">

<!-- iPhone (Retina) -->
<link href="http://www.example.com/mobile/images/apple-startup-iPhone-RETINA.jpg" media="(device-width: 320px) and (device-height: 480px) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">

<!-- iPhone 5 -->
<link href="http://www.example.com/mobile/images/apple-startup-iPhone-Tall-RETINA.jpg"  media="(device-width: 320px) and (device-height: 568px) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">

<!-- iPad Portrait -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-Portrait.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: portrait) and (-webkit-device-pixel-ratio: 1)" rel="apple-touch-startup-image">

<!-- iPad Landscape -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-Landscape.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 1)" rel="apple-touch-startup-image">

<!-- iPad Portrait (Retina) -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-RETINA-Portrait.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: portrait) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">

<!-- iPad Landscape (Retina) -->
<link href="http://www.example.com/mobile/images/apple-startup-iPad-RETINA-Landscape.jpg" media="(device-width: 768px) and (device-height: 1024px) and (orientation: landscape) and (-webkit-device-pixel-ratio: 2)" rel="apple-touch-startup-image">

If creating a Web App for iPad compatibility it's recommended that both Landscape and Portrait sizes are used.

Answer 2

The lack of documentation certainly is frustrating. I found a solution and blogged about it here: http://paulofierro.com/blog/2011/8/31/icons-and-splash-screens-for-ios-web-apps-retina-displays-also-welcome

Basically the sizes property and media queries will not work. You have to inject the high-res startup image via JavaScript once your page is loaded. Hacky but works.

Answer 3

It seems at this point in time, Apple does not support a retina display resolution startup image. According to their docs ...

On iPhone and iPod touch, the image must be 320 x 460 pixels and in portrait orientation.

Nothing is stated in that article about supporting high-res startup images.

Another good discussion of this issue can be found here .